This study was initiated to examine the effects of two polychlornated biphenyl (PCB) isomers (2,4,5,2',4',5'-PCB and 3,4,3',4',5'-PCB and a commercial PCB mixture on the in vitro metabolism of benzpyrene (metabolic profile) of benzpyrene metabolites) and covalent binding of benzpyrene to macromolecules in skin and other extrahepatic tissues.